He fires Blackwood after telling her, team leader Naomi Lay and Johnson in the boardroom that he "has had enough of ...washerwomen arguing with each other".

Blackwood said: "I've no regrets about turning down MI5. Five days before filming started it was made clear to me that it was one or another. I couldn't choose both.

"I really thought about it, and for me there's still no regrets."

She said of Sir Alan: "He does exactly what it says on the tin. I thought that he'd not be as scary as all that and might be a bit of a pussy cat, but he's not. I've got a large amount of respect for him."

The former Transport Development Manager has lined up a job with an engineering consultancy and is also hoping to market a yachting product patented by her father-in-law.